Davit mechanism



Nov. 4, 1952 A. DE F. WEBSTER 2,616,102

DAVIT MECHANISM Filed March 2, 1946 5 Sheets-Sheet l Nov. 4, 1952 A. DE F. WEBSTER 6,

I DAVIT MECHANfSM Filed March 2, 1946 5 Sheets-Sheet 2 Nov. 4, 1952 A. DE F. WEBSTER 2,616,102

DAVIT MECHANISM Filed March -2, 1946 5 Sheets-Sheet 4 [NVEN TOR.

/76M Al-Tm Nov. 4, 1952 A. DE F. WEBSTER DAVIT MECHANISM 5 Sheets-Sheet 5 Filed March 2, 1946 INVENTOR.

Patented Nov. 4, 1952 UNITED STATES PATENT OFFICE Alan:deaForestlWebster, Glen Cove, N. .Y., assignor ato. The Izandley Company; Inc., New. York, N. .Y., rat-corporation of New Jersey pucatim'Marc-he, 1946, SeriaI Ni651570 The inventionaims-primarily to provide a davit mechanism having movable parts which may be readily adjusted mechanically between anidle or load stowing position *wherein "it is nested, so to speak-above the "deckpand a' -load shifting positiomwherein the boom ofthe-'davit projects out beyond the deck as needed to raiseor -lower -a lifeboat or'other'load. As-Onefeature; the davit is preferably so constructed that during its movement to load-'stowing posit-ion'as aforesaid energy is stored -upfor 'use'in adjusting the movable parts of the davit 'toloa'd shifting position when desired. Other features and-advantages of the invention will bein part obvious and in" part specifically referred to' in the description hereinafter contained which, taken in conjunction with the accompanying "drawings; discloses a preferred form of 'davit-capableof operating in accordance "with the invention. '-The disclosure however should be considered asmerely'illustrative of the iprincipleszof "the invention in its "broaderjaspects.

. In its preferred form the-invention involves the use of a stationary main supporting'structure which is secured tothe deck, "and one or more boom supporting track members "which 'lie' ad- "jac-ent andsubstantiallyparallel to thesupporting 'structurev'vhen the 'davitlisin' loadstowing position. In adjustingthe'davit to load'shifting'posi- 'tlonfthese rail'members' are. tiltedwithirespect to the supporting structure? so as toassume a posi- "tion inclined downwardly toward theiedge' of the "deck; and preferably are alsoshifted' bodilywi-th "respect to the"supporting-1'structure so that their "outboard. endsiproj ectoutwardly' beyond the "deck. The boom of the "davitrispreierably slidableor rollable' along'the track membersabove described, in such manner that'ithe boom" is located at the inboard en'd ofthe tracks when" the latter are in nested'or load stowingposition, the boom" being moved: along thetracks iout'to the" outboard projectingen'ds thereof 'wherf'thetdavit is adjusted'to loadshifting'po'sition. Conversely when'the davit i adjusted from load shifting to load 'stowing position; the boom is moved*uptheincline-of the tracks from "theoutboard to'inboardends'thereof, and the tracks themselves are moved; inboard and adjusted back to a nested position adjaeent and substantially parallel to'thesupporting str-ucture. Preferably: an tenergy storing mechanism, :which mayautilizaa compressiontspringp weight, pneumatic-pressure cylinderorithe likegis so related ztolthe .movable-par-ts ofithe davit Lthat energysis :storeditherein whemthe d'avit iszadjustedltctload stowing positicmpsotthatatmsi-energysisiavailable .to impartv movement to the movable parts of the :spectively on .the broken lines4-4, 5- -5 and Fr-6 of Fig. 3, lookinglinzthetdirection of the arrows.

Fig. '7 is a general plan view of tWoof the davits of the type shown in Figs. 41 to 6, said davits being shown in load stowing positionand with a lifeboat. in stowed relation thereto.

Fig. '8 is.-a-detail-.section taken parallel tothe "plane 0t Figs. 1 and-2, through the boom member .of vthe. davit and showin -more particularly the details *otalocking mechanism which may be used in practicing the invention.

.Referring now more-specificallyto the form of the invention illustrated: in the drawings,. I

.have shown a supporting structure ',consisting primarily rot-aypairzofxchannel beams land.2

having.crosstpiecess3z=andv4 (Fig. 1) underlying themzand resting .zupon a deck 5, the beams land 2 running crosswise ofithe deck. in' such manner that their outerlendsare locateclnear the upper side edgefi of the ship hull.

. A'.pair' of traclc members; 1 and;8. shownin the general form ofwchannelcbeams are mounted between and. somewhat above; the 18V611'0f the supporting structure beams I and 2. Aspreviously statedthese track rzmembers I am-1 :8 .are so mounted with respect. to the supporting. structure that they may assume a position inclined thereto, andpreferablyaarezalso bodily movable withrrespect to the supporting. structure to assume. either a position wherein their-outboard ends project 'out. beyond the hulllfi flora position wherein they are-within the confines of the hull. v=Initheqillustrated form this .is :accomplished by providing the beams l and 2 at theirouter. ends .With bearin posts' 9 and :l 6 respectively (Fig.4) ,1 in which. are Journaled rollers l I; and. l'2a respectively. These rollers lLan'd l2-run elongated guide-ways. 13 and 1.4 respectively: on'thetracks 'l ande8 so that the trackmembers I l and; 8 :may; be movedzbodily alongi-the supporting structure: andrmay'a alsotiit tozthe'einclined positioni'showminrEigfl in'zw-hich their outboard ends project outwardly beyond the hull 6. As shown, the tracks 1 and 8 are connected together by cross braces 811 located underneath them.

Mechanisms are provided to guide the track members I and 8 in moving between the positions shown respectively in Figs. 1 and 2, and since the mechanisms used for each track may be the same, a description of one will serve for both. As shown in Figs. 1, 2 and 3, each of such motion guiding mechanisms includes a lever l of somewhat H-shape, having its lower ends pivotally connected by a pin IE to a bearing lug ll (Figs. 2 and 3) extending up from the supporting structure. At its upper end, each of the levers l5'is pivotally connected by a pin 18 (Fig. 1) to a bearing lug 19 (Fig. 1) extending up from the corresponding tracks I or 8 (Figs. 2 and 3). At an intermediate point, lever I5 is pivotally and slidably connected to a thrust rod 20 (Figs. 2 and 3) by means of a pin 2| which works in slots 22 in lever I5 and passes through the adjacent forked end of rod 20 as shown in Fig. 3. As also shown best in this figure, a roller 23 is also journaled on the pin 2|. As the track members 1 and 8 move from their load shifting position shown in Fig. 2 to the load stowing position shown in Fig. 1, their corresponding rollers 23 engage with and roll along inclined surfaces 24 of stationary guides which extend up from the supporting beams l and 2.

As previously mentioned the davit is preferably provided with devices for absorbing or storing energy as the moving parts move toward the load stowing positions shown in Figs. 1 and '3, in such manner that the energy thus stored may be applied to assist in moving these parts back from load stowing position to load shifting position when next required. In the illustrated form of the invention these energy storing devices take the form of springs which are compressed as the track members move toward the positions shown in Figs. 1 and 3. As shown best in Fig. 3 each of the thrust rods 20 above mentioned works in a cylinder 25 which is pivotally supported at its inner end by pins 26 journaled in brackets 21 extending up from the main supporting beams l and 2. A collar 28, fastened to the rod 20, compresses a powerful helical spring 29 as the track members move into the load stowing position shown in Fig. 1, thus storing energy in spring 29. Spring 29 is made powerful enough so that when the moving parts are released for movement toward the load shifting position shown in Fig. 2, as hereinafter described, the energy stored in spring 29 will be sufiicient to produce the initial stage of such movement.

" As shown in Fig. 3, a positively driven operating mechanism is also provided to produce the above initial movement if spring 29 should fail. For this purpose a screw threaded spindle 39 is provided, about which the rod 20 normally slides freely. As shown in the upper right hand portion of Fig. 3, the threaded spindle 30 may be rotated when desired by a hand crank 31 connected to the spring through appropriate sprocket gearing 32 and bevel gears 33 and 34. An internally threaded nut 35 having a clutched toothed face, is engageable with a hub 35 on the inner end of rod 20 having a complementary clutch toothed face. In case the spring 29 should fail, rod 20 will move far enough to the right (as the parts appear in Fig. 3) for hub 36 to engage with the internally threaded nut 35 above men- 4 tioned. Then crank handle 3! may be rotated to move the nut 35 to the left as the parts ap pear in Fig. 3, thus forcing rod 20 to the left and producing the initial movement of the moving parts toward their load shifting position, as a substitute for the stored up energy in the spring which will normally be utilized for this purpose.- A hollow boom member 40 is carried by the tracks or intermediate supporting members 1 and 8, preferably as previously stated in such manner that when the davit is in the load stowing position shown in Fig. 1, the boom 40 is lo-- cated at the inboard end of track members I and 8, and is moved to the outboard end of such track members as the davit is moved to the load shifting position shown in Fig. 2'. As shown, the boom 40 is provided with rollers 4| (Fig. 6) located near its inner end and carried by a spindle 42 passing through the boom member, these rollers runing within the track members I and 8. Similar rollers 43 (Fig. 5) are located at the outer end of the lower portion of boom member 40, these latter rollers being mounted on a spindle 44 which passes through the boom member.

In the form shown the position of the boom member 40, and of the track members 1, and 8 is controlled by the aid of the hoisting mechanism which is used to raise and lower the load with respect to the davit, this hoisting mechanism being operated by an appropriate winch as indicated generally at A in Fig. 7, and being connected to the various parts of the davit by cables .and guide sheaves as now to be described. As shown best'in Fig. 3the hoist cable 45 is anchored at one end by a turn-buckle 46 to the track member 8. From this point, cable 45 passes under a sheave 41a located part way up the boom member, and from thence over further sheaves 4'! and 48 at the overhanging upper end of the boom member. From thence, cable 45 passes around under a further sheave 49 (Fig. 3) constituting part of the tackle block 50 which carries the load, then over a further sheave 5| at the outer end of the boom on the opposite side thereof with respect to sheave 48. Then cable 45 passes over a further sheave 52 which is on the opposite side of the boom from sheave 41, and then around a further sheave 53 lower down on the boom, which is opposite a sheave 41a. From sheave 53, cable 45 passes to a sheave 54 on rail member I, and then around a sheave 54a (see Fig. 5) on the rail member I, from whence cable 45 passes to a further sheave 55 (Fig. 5) mounted in a bracket 56 extending up from the supporting beam I. Then the cable passes around a sheave 51 (Fig. 3) which may be appropriately supported from any convenient part of the stationary structure, after which the cable 45 passes to the winch as indicated in Fig. 7.

This figure shows two hoisting cables 45 and 45a 7 leading to the two davits which are located respectively at the opposite ends of the lifeboat.

If it be assumed that the davits and load to be stowed are in position shown in Fig. 2. winding up of the winch A will continue to lift the load until tackle block 50 comes up against the overhanging outer end of boom member 40. Then further tension on cable 45 will cause the portion thereof which passes around the sheaves on boom member 40 to shorten up, thus moving boom member 40 from the full line position shown at the left of Fig. 2, to the dotted line position indicated at the inner end .of track Further tension on cable 45 will cause the portion. thereof which is. between .the sheaves amate- Bic and-55 to shorten up, thus withdrawingi the tracks "I and '8" from the 4 overhanging position shown in Fig. 2, tea position *wherein' (a1s"- the parts appear in Fig.- 1), the "roller'l'i' engages the left hand end of guideway i3;- Duringthis stage the tracks Tand 8 will swing partially down toward the position shown inFi 'g; 11- Fur ther tension on the cable-thereupon swings the inner ends of tracks 1 and-8 downwardly about rollers i l and l2=' as pivots, fully-into the position shown in Fig. '1'.

During the above describedmetractingmovement of tracks 1 and 8; thelever s' liswing to the right from the position sho'wn-in F-ig 2, about pins 16 as pivots, andthis movement forces'a-the rods zt furth'er into cylinders thus compress ing the" springs -2:-'9- within such; cylmders; and storing energy therein. Thenlduring ."the final angular movement of tracle members I *and- 8 down to the position shown in Fig. i5 are-swung further downwardly, 't compressing the springs- 29' in cylinders 25.-

As shown in Figs, 1 and 2- the track members 7 and 3 may be provided with shoulders Bdwvhich are engaged by the keel of a lifeboat as-theboom member 39 moves toward-its loa-d 'stowing position, thus causing the lifeboat totiit inwardly as shown-in Fig. 1-aslthe davit assum'es..ifinal lead stowing position. In .final stowedi position the lifeboatmay restuponcradlesjlwas best shown in Figs. 2.and 37, being preterablylashedtin this position asiis well known in; the artian'd. .ac cordingly need not be described. herein in detail.

When the lifeboat or other load is to be launched or unloaded, tension on the cables and 45a is slacked on gradually, and the springs in cylinders 25 are made powerful enough as above described so that the energy stored therein is sufficient to tilt the tracks up to inclined position. Further easing off in the'tension on cables 45 and 45a causes the boom to slidedown tracks land 8 to the outboard position shown in Fig. 2', assisted by the weightiof the load itself. Still further slacking of 1 cable 45 causes the-load to be lowered from boom 46.

Preferably a locking. mechanism is provided for the boom 45, which maybe actuated when the boom and track members are in the load shifting position shown in Fig. 2 to prevent the boomfrom moving up the incline of the tracks until the load or the tackle block which carries the load, has been hoisted fully up to the overhanging outer end of boom 4. In the illustrated form of the invention this locking mechanism is automatic in its action, and includes a roller 62 (Fig. 8) at the lower outer end of boom 40, which roller is mounted in a link 63 pivoted within the boom at pin 64. Except when boom member 40 is at the outer limit of its path of travel, roller 62 rides over the top of a guide rail 65 located between the track members I and 8. A further link 65 within boom member 40 is also connected at its lower end to roller 62, and at its upper end to a bell crank lever 61, which latter is in turn connected to a link 68 pivotally connected to links 19 and H. Link 70 is pivoted about pin 72 and link H is pivotally connected to the end of a forked dog 13 which is pivoted about pin 14 which also carries sheaves 48 and 5|. The upper end of the tackle block 50 may be provided with an upper cross bar I5 (Fig. 8) which moves dog 13 anti-clockwise from the position shown in full lines in Fig. 8 when the load is lowered. This movement will cause the roller 62 to move down to locking position with 62 respect to"=a shoulder vfirat. theaouter end of:rail 65, thus *preventing the boom frommoving up the incline ofthe tracksso long as. the load is being lowered-4 This locked:condition-persists until the load; or tackleblockfit; has been fully raised, at which stageithe cross-bar 15. .movesmdog l3 clockwise to the p'ositionshown -full linesin Fig. 8, thus raising :roller '62 outcof locking en'- gagementwith. shoulder 15'; Thereupo'm the load being 'fullyraised', theboom memberand the load imay beiipulled up theineline. of tracks I and 8* by "further tightening up. on thethoist cables, andhthe tracks moved angularly to load stowing. position, as above described;

:Aieonstru'ction. of thelab'ove' type occupies .rel'a-e tively small headroom, .since'th'e movable parts nest 'closely-downtoward the deck whentheda'vit isr'in. load stowing position but may. be vreadily tilted to load shifting position when required;

While the invention has been. disclosed, as carried out. by davits of the above described specific construction, it should. be understood that many changes maybe made thereinwithout departing-from the-invention-in its broader aspects, within the scope of the appendedclaims.

I claim: I

1. A. davit of thecharacter described including a supporting structure: an intermediate boom supporting member carried by said supporting structure. and" mounted thereon for angular movement between a .load: stowing, position wherein itlies adjacent said supporting structure and a load'rshiftingposition wherein it is 16134? tively 'moreinclined to said supporting structure, a: boom member carried; by. said. intermediate supporting member; a .rocking lever. connected tosaid intermediateboom supporting member to guide its angular.movements aforesaid, and compression spring means connected with said-lever to. store .up. energy in said spring .whenisaid intermediate supporting'member' moves. from its secondto its first above mentioned position :and apply. the thus stored "energy to said leveras said intermediate supporting member :moves from its firstto its second "above mentioned position.

2 Adavit 'orthe character described including a. supporting structure, an intermediate" boom supportingmember carried by. said supporting structure, and mounted thereon. .for. movement between :aloa'd stowing positionand :a load Shift? ing position wherein it is relatively more inclined to said supporting structure, means connected to the inboard portion of said intermediate member for moving the latter upwardly to load shifting position, a boom member carried by said intermediate supporting member, energy storing mechanism energized by movement of said intermediate supporting member to load storing position, load lifting and lowering mechanism operating to move said intermediate supporting member from its second to its first above mentioned position, said energy storing mechanism being connected to said intermediate member moving means.

3. A davit of the character described including a supporting structure constructed to be mounted on a deck, a rail member having its outer end portion tiltably engaged with said supporting structure at a point adjacent the edge of said deck, said rail member when in load stowing position lying substantially parallel to and adjacent said deck throughout the length of the rail member, mechanism connected to the inboard portion of said rail member for moving the latter upwardly to a load shifting position wherein the rail memgamma ber inclines downwardly toward the edge of the deck, a boom member carried by said rail member, load lifting and lowering mechanism including sheave members mounted on said boom and rail members, and cable means guided by said sheaves, an energy storing device connected to said first mentioned mechanism to store up energy inrsaid device upon movement of said first mentioned mechanism from load shifting to load stowing position, said load lifting and lowering mechanism operating to move the boom member and the rail member from load shifting to load stowing position, thereby to store energy in said device to move said first mentioned mechanism and said rail and boom members upwardly from the load stowing to load shifting position.

4. A davit of the character described including a supporting structure constructed to be mounted on a deck, a rail member having its outer end portion tiltably engaged with said supporting structure at a point adjacent the edge of said deck, said rail member when in load stowing position lying substantially parallel to and adjacent said deck throughout the length of the rail member, mechanism connected to the inboard portion of said rail member for moving the latter upwardly to a load shifting position wherein the rail member inclines downwardly toward the edge of the deck, a boom member slidably carried by said rail member to afford movement between an inner load stowing position and an outer load shifting position, load lifting and lowering mechanism including sheave members mounted on said boom and rail members and cable means guided by said sheaves, said last mentioned mechanism operating to move the rail member from load shifting to load stowing position and to slide said boom member from outer to inner position with respect to said rail member.

5. A davit of the character described including a supporting structure constructed to be mounted on a deck, a rail member having its outer end portion tiltably engaged with said supporting structure at a point adjacent the edge of said deck and beingalso slidably engaged with said supporting length of the rail member, mechanism connected to the inboard portion of said rail member for moving the latter upwardly to a load shifting position wherein the rail member inclines downwardly toward the edge of the deck and shifting said rail member to its aforesaid outer position, a boom member carried by said rail member, load lifting and lowering mechanism including sheave members mounted on said boom and rail members and cable means guided by said sheaves, said last mentioned mechanism operating to move the boom and rail members from their aforesaid load shifting to load stowing position.

6. A davit of the character described including a supporting structure constructed to be mounted on a deck, a rail member having its outer end portion tiltably engaged with said supporting structure at a point adjacent the edge of said deck, said rail member when in load stowing position lying substantially parallel to and adjacent said deck throughout the length of the rail member, a lever mechanism connected to the inboard portion of said rail member for moving the latter upwardly to a load shifting position wherein the rail member. inclines downwardly toward the edge of the deck, and a spring mechanism connected to said lever mechanism to store up energy in said spring as the rail member moves from load shifting to load stowing position, a boom member carried by said rail member, and cable and sheave means for shifting said boom andrail members from load shifting to load stowing position.

ALAN DE FOREST WEBSTER.

' REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

